I see this as a big problem. As to the massive amount of data generated:
(1) Where are you going to store it?
You store it in a storage system.
If you're a large movie studio, you can probably afford to throw a million dollars at a heavy duty storage system, and another million dollars at a backup system.
(2) How much time will it take to transfer it?
Yep, that's probably a bother, but it might still be easier than digitizing chemical film footage.
(3) But, most importantly, it is easy to say "frame-grabs." But how does any pro photographer other than a large-staff commercial studio sift through thousands or tens of thousands of frames, even if you manage to store--transfer--store that massive amount of data?
We're talking
movies here.
You watch the movie, you select a few time sequences where you think you might find the relevant stills to extract, and then you narrow it down from there.
Spin the wheel forward and backward to see which frame to grab, and save the one or two that does it for you.
Basically, you - and many others in this forum - are viewing this from the wrong side; from the still photographer's closed universe.
Turn it around, and consider it from a movie production point of view:
You get a fully digital workflow, from recording to the movie theatre.
George Lucas took advantage of this for "Attack of the Clones" and "Revenge of the Sith", as the first major movie director in history.
And yes, Sony, Panasonic et al probably feel the pressure.